Randomization of the array modifier
Result with Particle System





Preparation


Create an Object (Cube) and bring it in the desired shape.
Create a Plane, subdivide it in Edit Mode (F6 for adjusting the number of cuts easily).
Add a Particle System to the Plane.




Setting up the Particle System


In the Physics Dropdown choose No.
In Render Dropdown choose Object and pick your "brick" you have created.







In the Emission Dropdown choose:


Emit from Faces
Grid
Enable Hexagonal Grid










Play around with the Resolution value in the Emission Dropdown and scale S your Plane along one Axis until you have a nice Pattern.







Randomize:


In the Emission Dropdown you can add a random Offset to the Grid locations
Enable the Rotation Dropdown and randomize softly the Particle Orientation